Air filters for prefiltration and final filtration for HVAC and general equipment protection can take many forms, depending on the particular application. One type of filter is a pleated filter, which is formed from a sheet of filter media folded into a series of pleats. One type of pleated filter, known as a minipleat filter, has smaller, closely spaced pleats. The peaks between adjacent pleats of a minipleat filter are spaced no more than 20 mm apart and typically range from 5.0 mm to 7.5 mm apart.
A pleated filter can be made from a variety of media. The size of the filter affects the choice of media. For example, for a minipleat filter, fiberglass is a suitable material. A synthetic, nonwoven filter media has been used, as described in U.S. Pat. No. 6,464,745.
Typically, minipleat or other pleated filter media are disposed within a hard or rigid plastic frame. The rigid frame is then mounted within the filtration equipment. The frame maintains the pleated filter media in the desired configuration and size and imparts some structural rigidity to the entire assembly.